Evaluation of Antioxidant Properties of Six Underutilized Edible Wild Fruits in Sri Lanka

Abstract

Protection against free radicals can be impeded by improving the dietary intake of antioxidants. Wild fruits and their products are a valuable source of antioxidant. Therefore, objectives of this study were to determine and compare different mode of antioxidant activities of six different underutilized wild fruits i.e. Calophyllum calaba (Keena), Syzygium cumini (Madan),Drypetes sepiaria (Weera), Syzygium caryophyllatum (Dan), Ficus racemose (Attikka) and Careya arborea (Kahata)found in natural habitats of Sri Lanka. Antioxidant properties of wild fruits were tested using different in vitro assays using 96 well micro plates. Free radical scavenging activity (FRSA), Ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC), total phenolic contents (TPC) and total flavonoid content (TFC) was determined by using standard procedures. Softmax Pro 5.2 v software was used to calculate antioxidant values. Results showed that 2,2- azinobis3ethylbenzothiozoline-6-sulfonic (ABTS+ ) and 1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging activity in all fruit types. DPPH and ABTS+ radical scavenging activity of selected wild fruits were in the range of 30.49±4.87 to 585.40±6.43 mg Trolox equivalents (TE)/g of extract and 43.08±02.89 into 435.30±6.62 mg (TE)/g of extract respectively. Calophyllum calaba recorded the lowest FRSA with the highest IC50 value in each assay. Total reducing potential of fruit extracts that was measured using FRAP revealed that significantly (P<0.05) higher value in Careya arborea (455.91 ± 33.94 mg TE/g of extract) while the lowest in Calophyllum calaba (12.35 ± 0.10 mg TE/g of extract). ORAC of selected fruit extracts were ranged from 7 to 25 mg TE/g extract. The highest TPC was recorded in Careya arborea (590.95 ± 22.17 mg gallic acid eq/g extract) followed by Ficus racemose (180.04 ± 5.09 mg gallic acid eq/g extract). Syzygium caryophyllatum recorded the highest TFC (13.56 ± 0.26 quercertin/g of International Conference of Sabaragamuwa University of Sri Lanka - 2017 Copyright © ICSUSL-Sabaragamuwa University of Sri Lanka 2017 325 extract) while Calophyllum calaba and Syzygium cumini showed the lowest TPC and TFC respectively. Overall results suggested that selected fresh wild fruits possess marked antioxidant activities and Careya arborea and Calophyllum calaba L recorded the highest and the lowest antioxidant activity showing the use of these wild fruits for prevention and management of oxidative stress associated chronic diseases in Sri Lanka.